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T. A. EDISON. TELEPHONE- TRANSMITTER.

No. 378,044. Patented Feb. 14, 1888.

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T; A. EDISON-.- a TELEPHONE TEANsMITTE No. 378,044. Patented Feb 14,1888'.

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. I UNITED {STATES ATENT OFFICE." I

THOMAS A. EDISON, OF MENLO PARK, NENV JERSEY.

TELEPHONE-TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 378,044, dated February14:, 1888. 7

Application filed October 14, 1885. Serial No. 179,368. (No model.) I

To all whom it may concern:

Be it known that I, THOMAS A. EDISON, of Menlo Park, in the county ofMiddlesex and State of New Jersey, have invented a new and usefulImprovement in Telephone-Transmitters, (Case No. 646,) of which thefollowing is a specification.

My invention relatesto electric telephonetransmitters, preferably of theclass employing carbon buttons; and my object is-to produce a simple andefficient multiple instrument of this character and an arrangement forworking multiple instruments in circuit which will be more effectivethan those heretofore proposed.

In the accompanying drawings, forming a part hereof, Figure 1 is avertical section of the transmitter; Fig. 2, a top view of theelectrodecarrier, Fig. 3, a view, principallyin diagram, showing thepreferred arrangement of the instrument in circuit; and Fig. 4, asimilar view of an arrangement that may be employed.

The case of the instrument is preferably of metal, made in two parts, AB, between which is clamped the diaphragm C, of metal or mica. The partB of the case comes to mouth-piece D. Centrally in part A of the case isa metal adjusting screw, E, which carries a metal plate, F. This plateis the carbon-button carrier. It is shown as carrying two carbonbuttons; but a greater number may be used. This plate F has on its facetwo circular receptacles with metal plates at a in their bottom. Thesereceptacles have rings 12 b of insulating materialsuch as hardrubber-which rings insulate the carbon buttons and superimposed platesfrom the carrier. Upon plates a a are carbon buttons cc, and above theseare metal plates d d, upon which bear the arms of a yoke, G. Points 6 onthe yoke-arms enter sockets f, of insulating material, carried by platesd d. The yoke G has on its back a central stud, g, which enters acentral opening in the diaphragm and is adapted to turn freely therein.-

The periphery of plate F is faced with insulation, h-such as hardrubberandupon this insulating-face are secured metal rings i i, one foreach carbon button. These rings are connected with the plates at d, asshown, ring 1; being connected electrically by a fine wire with plate (Iand ring 2" with plate (1. Insulated bear on rings t i.

If three or more carbon buttons are employed, the plate F will have acorresponding number of receptacles, and the arms of the" yoke, therings on the periphery of the buttoncarrier, and the insulatedbinding-posts and springs will be increased correspondingly in number.The instrument has a binding-post, L, which is not insulated from themetal case.

To adjust the instrument, the screw E is turned, the springs 70 ithaving a broad enough bearing on rings '0 i to permit this to be doneand the yoke G turning on the diaphragm.

In use I prefer to arrange the carbon buttons in circuit with differentprimary induct-ioncircuits, the induction coil having two primarycircuits and one secondary circuit, as shown in Fig. 3.

K is the induction-coil, having two primaries, Zm, and a secondary, n.The primaries bindingposts H H have springs k k', which are preferablythe same in resistance, size of wire, and number of turns, the wires forthe two primaries being wound together, although for clearness inillustration-they are shown as separated in Fig. 3. The wires 1 2 to theinsulated binding-posts are connected with one end of the two primarycoils l m, while at the other end the primary coils are connected to acommon wire, 3, connected wit-h the basepost. the receiver M and theground.

I prefer to employ two separate batteries, N 0, one in the circuit ofeach wireland 2; but these batteries may be combined in one, P, andlocated in circuit of wire 3, as shownin dotted lines. Thetransmitter-circuit, assuming the two separate batteries N O are used,will be from N O by wires 1 2 through prima- The line L passes throughsecondary to ries Z m, by wire 3 to base, and by'screw E to plate F,through plates or a,carbon buttons 0 0, plates 61 d to rings t" z',springs it is, insulated posts, and wires 12 back to batteries. 'By thearrangement shown in Fig. el: a simple induction-coil, Q, is employed.The line passes through thesecondary and receiver to ground. The simpleprimary circuit is connected with the two insulated binding-posts bywires 1 2, and a single transmitting-battery, R, is employed. Thisthrows the carbonbuttons into series, the circuitbeing down through onecarbon button, across plate F, andup throughthe other carbon button.Forithese connections the base-post L is not connected with the circuit.

What I claim is- 1. In a multiple electric telephonetransmitter, thecombination of two or moresets of electrodes supported by a commoncarrier mounted on a central adjusting-screw and turning therewith,substantially as set forth.

2. In a multipleelectric telephone-transmitter, the combination of twoor more sets of electrodes supported by a common carrier mounted on andturning with a central adjusting-screw, with a turning-yoke bearing onsuch electrodes and connected centrally with the diaphragm,substantially as set forth.

3. In a multiple electric telephone-transmitter, the combination of twoor more sets of electrodes mounted upon a common metallic support andhaving separate insulated hearing or contact plates connected withinsulated circuit-connections, substantially as set forth.

carrier-plate with which said separate contacts are electricallyconnected, springs bearing on such insulated rings, and insulatedbinding-posts for such springs, substantially as set forth.

This specification signed and witnessed this 9th day of January, 1885.

THOMAS A, EDISON.

\Vitnesses: I

H. WJSEELY, '1. G. GREENE, Jr.

